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Astrophysicists Discover Tilt in Kuiper Belt, Hinting Planet Y

10/18/2025

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Summary

Story summary

Princeton University astrophysicists report a 15-degree tilt in the Kuiper Belt, hinting at an unseen planet called Planet Y.
The tilt appears among objects 80–200 astronomical units from the Sun, with 96–98 percent confidence.
Researchers used a new method to analyze 154 Kuiper Belt objects, finding a flat plane if no planet exists.
Simulations indicate a Mercury-to-Earth–sized planet could explain the warp, advancing the search for outer worlds.

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Story summary

Princeton University astrophysicists report a 15-degree tilt in the Kuiper Belt, hinting at an unseen planet called Planet Y.
The tilt appears among objects 80–200 astronomical units from the Sun, with 96–98 percent confidence.
Researchers used a new method to analyze 154 Kuiper Belt objects, finding a flat plane if no planet exists.
Simulations indicate a Mercury-to-Earth–sized planet could explain the warp, advancing the search for outer worlds.